While the not most-used feature among our Google Apps Premier Edition customers, offline Gmail is available and is no longer considered Beta. Offline Gmail lets you compose and read your email without an Internet connection and without using other programs like Microsoft Outlook.
Recently, Google enhanced some of the features that let you manage messages for offline use. You have more flexibility to download messages by time frame for offline use. You can also manage download messages with specific labels — all or by time frame as well.